The table below summarises the plug types, voltage and frequency of electrical current in both Brunei and Iran.
|Frequency of electrical current||50Hz||50Hz|
Brunei uses Plug Type G.
You will need this adaptor:
Socket Type G
(Brunei) to Plug Type C
The voltages found in Brunei (240V) and Iran (230V) are not exactly the same, but the difference is tolerable, so you should not need a transformer.
The frequency found in Brunei and Iran is exactly the same (50Hz). Timing devices and appliances that use motors will function as expected under this frequency.